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This Article Full Text Full Text (PDF) All Versions of this Article: 79/2/274    most recent biolreprod.108.067637v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Bridger, P. S. Articles by Pfarrer, C. PubMed PubMed Citation Articles by Bridger, P. S. Articles by Pfarrer, C. Agricola Articles by Bridger, P. S. Articles by Pfarrer, C.

Integrin Activation in Bovine Placentomes and in Caruncular Epithelial Cells Isolated from Pregnant Cows

Institute for Hygiene and Infectious Diseases of Animals,² Justus-Liebig-University, 35392 Giessen, Germany Department of Veterinary Integrative Biosciences,³ Texas A&M University, College Station, Texas 77843 Department of Obstetrics and Gynecology,⁴ Justus-Liebig-University, 35385 Giessen, Germany Department of Anatomy,⁵ Veterinary University Hannover, 30173 Hannover, Germany

ABSTRACT

In the bovine synepitheliochorial placenta, restricted trophoblast invasion requires complex interactions of integrin receptors with proteins of the extracellular matrix (ECM) and integrin receptors of neighboring cells. Activated integrins assemble to focal adhesions and are linked to the actin cytoskeleton via signaling molecules including alpha-actinin (ACTN), focal adhesion kinase (PTK2 or FAK), phosphotyrosine, and talin (TLN1). Aims of this study were to assess integrin activation and focal adhesion assembly within epithelial cells of bovine placentomes and low-passage (not transformed) placentomal caruncular epithelial cells cultured on dishes coated with ECM proteins. Immunofluorescence analysis was performed to colocalize the signaling molecules ACTN, PTK2, phosphotyrosine, and TLN1 with each other and with beta₁-integrin (ITGB1) in placentomal cryosections throughout pregnancy and in caruncular epithelial cells in vitro. Antibody specificity was confirmed by Western blot. Cells were cultured on uncoated dishes, and the dishes were coated with fibronectin (FN), laminin (LAMA), and collagen type IV (COL4), thereby statistically assessing cell number and qualitatively assessing the expression pattern of ITGB1, phosphotyrosine, and TLN1. Results demonstrated integrin activation and focal adhesion assembly in the placentome and that low-passage caruncular epithelial cells maintain integrin-associated properties observed in vivo. Expression and/or colocalization of signaling molecules with ITGB1 confirmed, for the first time, integrin activation and participation in "outside-in" and "inside-out" signaling pathways. The prominent role of ECM, and FN in particular, in integrin signaling is supported by the in vitro enhancement of proliferation and focal adhesion expression. Thus, this in vitro model provides excellent potential for further mechanistic studies designed to elucidate feto-maternal interactions in the bovine placentome.

-actinin, bovine placentome, caruncular epithelium, extracellular matrix, FAK, fibronectin phosphotyrosine, integrin, integrin activation, pregnancy, talin